As a user interface (man-machine interface) device that enables a user input with respect to a computer, various apparatuses such as a mouse, a joystick, a trackball, and a touch panel, have been provided. In recent years, a user interface device that enables a user input in response to a body movement by detecting the body movement (gesture), such as a data glove, a data suit, or the like, has been also developed. A user can operate a computer with an intuitive feel by such a user interface device.
For example, in PTL 1 described below, a technology that facilitates an operation input by a user's gesture is proposed. By the proposed technology, based on resolution of a distance sensor, three-dimensional display performance of a display, and a measurement distance of an instruction point such as a finger of the user's hand in the depth direction, a parameter for determining sensitivity of detecting a movement of the instruction point in the depth direction is adjusted. Then, by calculating the distance of the instruction point in the depth direction based on the adjusted parameter, the operation input by the user's gesture is recognized.